rt

#include<bits/stdc++.h>
using namespace std;
double h(double a,double b,double c)
{
	int p=0.5*(a+b+c);
	return sqrt(p*(p-a)*(p-b)*(p-c));
}
int main(){
	double a,b,c;cin>>a>>b>>c;
	printf("%.1f",h(a,b,c));
}

#include<bits/stdc++.h>
using namespace std;
float h(float a,float b,float  c)
{
	int p=0.5*(a+b+c);
	return sqrt(p*(p-a)*(p-b)*(p-c));
}
int main(){
	float a,b,c;cin>>a>>b>>c;
	printf("%.1f",h(a,b,c));
}

这俩都不行